• 제어로봇시스템학회논문지
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• 제20권9호
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• pp.984-993
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• 2014

In this paper, we propose a design for an efficient hybrid LED street lighting management system using standalone solar photovoltaic. The proposed efficient hybrid LED street lighting management system was composed of hybrid power conditioning system, gateways, LED street lights and a monitoring server. The hybrid power conditioning system was designed to charge produced power by solar photovoltaic panels in day time, and supply power to the LED street lights in night time. If there is insufficient power, the system was designed to operate using firm power, because the system utilizes photovoltaic power. A system control algorithm allied to the lighting management system, and experimented by being configured to the functions that are able to perform real-time monitoring and remote control through the lighting management system even when absent. In the result of the efficiency analysis of the hybrid lighting management system proposed in this paper, we were able to increase the energy efficiency compared to existing lighting control systems by reducing power consumption and electricity costs.

• Journal of Power Electronics
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• 제16권2호
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• pp.666-674
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• 2016

In this paper, a high efficiency satellite electrical power supply system is proposed. The increased efficiency of the power supply system allows for downscaling of the solar array and battery weight, which are among the most important satellite design considerations. The satellite power supply system comprises two units, namely a generation unit and a storage unit. To increase the efficiency of the solar array, a maximum power point tracker (MPPT) is used in the power generation unit. In order to improve the MPPT performance, a novel algorithm is proposed on the basis of the hill climbing method. This method can track the main peak of the array power curve in satellites with long duration missions under unpredicted circumstances such as a part of the array being damaged or the presence of a shadow. A lithium-ion battery is utilized in the storage unit. An algorithm for calculating the optimal rate of battery charging is proposed where the battery is charged with the maximum possible efficiency considering the situation of the satellite. The proposed system is designed and manufactured. In addition, it is compared to the conventional power supply systems in similar satellites. Results show a 12% increase in the overall efficiency of the power supply system when compared to the conventional method.

• 전력전자학회논문지
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• 제11권6호
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• pp.535-542
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• 2006

저궤도 인공위성 전력계 시스템의 설계 및 해석을 위한 태양전지 전력조절기의 대신호 안정도해석을 수행한다. 태양전지 전력조절기에서 제어가능한 모든 방법에 따른 태양전지에서 바라본 태양전지 전력조절기의 부하특성을 분류하고, 상태공간해석을 이용하여 태양전지 시스템의 대신호적 안정도를 해석한다. 또한, 본 논문에서는 태양전지 전력조절기의 부하특성을 정전력부하에서 정저항부하로 변환하여 대신호적인 안정도를 확보하는 비선형변환을 제안한다. 제안된 변환기법을 통해 최대전력점 추적제어나 배터리 충전제어 및 전류분배제어가 가능한 병렬 모듈 태양전지 레귤레이터에 적합한 단일 전류 제어기를 구성한다. 제안된 대신호 해석과 저항제어를 검증하기위해, 200W급 태양전지와 100W급 태양전지 전력조절기 두 모듈을 병렬로 구성하여 실험하였다.

• Journal of Power Electronics
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• 제7권2호
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• pp.174-180
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• 2007

In this paper, a simple control method for two-stage utility grid-connected photovoltaic power conditioning systems (PCS) is proposed. This approach enables maximum power point (MPP) tracking control with post-stage inverter current information instead of calculating solar array power, which significantly simplifies the controller and the sensor. Furthermore, there is no feedback loop in the pre-stage converter to control the solar array voltage or current because the MPP tracker drives the converter switch duty cycle. This simple PCS control strategy can reduce the cost and size, and can be utilized with a low cost digital processor. For verification of the proposed control strategy, a 2.5kW two-stage photovoltaic grid-connected PCS hardware which consists of a boost converter cascaded with a single-phase inverter was built and tested.

• Journal of Advanced Marine Engineering and Technology
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• 제29권3호
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• pp.319-324
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• 2005

This paper reports the performance of Wind-PV(Photovoltaic) hybrid system. The output power of PV is affected by the environmental factors such as solar radiation and cell temperature. Also, the output power of wind system is generated with wind power. Integration of Wind and PV resources, which are generally complementary, usually reduce the capacity of the battery. This paper includes discussion on system reliability, power quality and effects of the randomness of the wind and the solar radiation on system design.

• 한국태양에너지학회 논문집
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• 제31권2호
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• pp.120-127
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• 2011

Solar array has the following nonlinear characteristic, such as whose output current increases, output voltage is reduced. For this reason, boost converter with solar array system is always controlled to remain on the maximum power point of the solar array. In this case, we are not focused on the output of the solar array and not consider efficiency of the boost converter, which is assumed reliable. But efficiency of the converter also should be considered, which affects the total efficiency of the overall solar energy system. In this paper, efficiency calculation of the boost converter using power balance method is proposed, which will be used for a powerful reference before hardware realization.

• Advances in Energy Research
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• 제1권2호
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• pp.97-106
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• 2013

This study designs and tests a photovoltaic system with distributed maximum power point tracking (DMPPT) methodology using a field programmable gate array (FPGA) controller. Each solar panel in the distributed PV system is equipped with a newly designed DC/DC converter and the panel's voltage output is regulated by a FPGA controller using PI control. Power from each solar panel on the system is optimized by another controller where the quadratic maximization MPPT algorithm is used to ensure the panel's output power is always maximized. Experiments are carried out at atmospheric insolation with partial shading conditions using 4 amorphous silicon thin film solar panels of 2 different grades fabricated by Chi-Mei Energy. It is found that distributed MPPT requires only 100ms to find the maximum power point of the system. Compared with the traditional centralized PV (CPV) system, the distributed PV (DPV) system harvests more than 4% of solar energy in atmospheric weather condition, and 22% in average under 19% partial shading of one solar panel in the system. Test results for a 1.84 kW rated system composed by 8 poly-Si PV panels using another DC/DC converter design also confirm that the proposed system can be easily implemented into a larger PV power system. Additionally, the use of NI sbRIO-9642 FPGA-based controller is capable of controlling over 16 sets of PV modules, and a number of controllers can cooperate via the network if needed.

• 전기학회논문지
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• 제58권3호
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• pp.486-495
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• 2009

This paper proposes a new methodology on reliability evaluation of a power system including solar cell generators (SCG). The SCGs using renewable energy resource such as solar radiation(SR) should be modeled as multi-state operational model because the uncertainty of the resource supply may occur an effect as same as the forced outage of generator in viewpoint of adequacy reliability of system. While a two-state model is well suited for modeling conventional generators, a multi-state model is needed to model the SCGs due to the random variation of solar radiation. This makes the method of calculating reliability evaluation indices of the SCG different from the conventional generator. After identifying the typical pattern of the SR probability distribution function(pdf) from SR actual data, this paper describes modelling, methodology and details process for reliability evaluation of the solar cell generators integrated with power system. Two test results indicate the viability of the proposed method.

• 한국추진공학회지
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• 제19권4호
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• pp.94-101
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• 2015

장기체공 무인기용 동력원으로 활용될 태양전지-연료전지 복합 동력원 통합 전 단계로 태양전지와 연료전지 개별 시스템에 대한 구성과 평가를 수행하였다. 태양전지 시스템은 Sunpower사의 C60 태양 전지를 활용한 모듈, 상용 태양광 MPPT 제어기, 그리고 리튬-폴리머 배터리를 이용하여 구성하고 평가하였다. 연료전지 시스템 운용을 위하여 $NaBH_4$ 가수분해를 이용한 수소공급장치의 재시동 특성을 확인하였다. 태양전지 시스템에 속한 배터리의 성능이 평균 -2.9 V/hour임을 확인하였다. 수소공급장치의 재시동 특성이 운용임무 조건에서 안정적인 성능이 나타남을 확인하였다. 본 연구를 통하여 제시된 임무조건에서의 각 단일시스템의 성능이 적합함을 확인하였다.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.920-926
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• 2011

본 논문에서는 신재생에너지 활용을 위한 다중 추적식 태양광 발전 감성형 LED 가로등을 제안한다. 제안하는 가로등 시스템은 다중 추적방식의 태양광 추적기능을 갖추고 있고 감성형 고품위 LED 램프와 제어회로를 사용하여 센서를 통해 입력되는 온도 및 습도를 기반으로 최대의 일조량을 받을 수 있도록 하였다. 신재생에너지 활용의 핵심 요소인 효율적인 축전지 활용을 위해 충방전 컨트롤러를 개발하였고 원격모니터링 기능 및 제어기능도 구현 하였다. 제안하는 가로등 시스템은 기존 기술에 비하여 추적 동작이 우수하고 에너지효율이 향상되었으며 기존에 개발되지 않았던 추적식 태양광 발전 시스템과 감성형 LED를 결합함으로써 차세대 가로등 시스템의 모델로서의 활용될 수 있게 하였다.